Add warning and link for no installed examples

CHANGELOG.md

@@ -10,7 +10,8 @@ All notable changes to this project will be documented in this file.
 ### Added
 
 - [Arduino CLI](https://arduino.github.io/arduino-cli/0.30/) version 0.30.0 is now bundled with the extension [#1584](https://github.com/microsoft/vscode-arduino/pull/1584). To use the bundled version of Arduino CLI, `arduino.useArduinoCli` should be `true`, and `arduino.path` and `arduino.commandPath` should be empty or unset. Additionally, prompts will appear to switch to the bundled version whenever the legacy Arduino IDE is used or manually specified Arduino tools cannot be found.
-- A warning will appear in the Board Configuration view when no boards are installed. This warning links to the Board Manager view to install boards. [#1592](https://github.com/microsoft/vscode-arduino/pull/1584)
+- A warning will appear in the Board Configuration view when no boards are installed. This warning links to the Board Manager view to install boards. [#1592](https://github.com/microsoft/vscode-arduino/pull/1592)
+- A warning will appear in the Arduino Examples view when no examples are installed. [#1594](https://github.com/microsoft/vscode-arduino/pull/1594)
 
 ### Changed
 

package.json

@@ -182,6 +182,12 @@
         }
       ]
     },
+    "viewsWelcome": [
+      {
+        "view": "arduinoExampleExplorer",
+        "contents": "No examples are installed. [Find additional examples online.](https://go.microsoft.com/fwlink/?linkid=2225276)"
+      }
+    ],
     "debuggers": [
       {
         "type": "arduino",

src/arduino/exampleProvider.ts

@@ -43,10 +43,18 @@ export class ExampleProvider implements vscode.TreeDataProvider<ExampleItem> {
         this._exmaples = null;
         this._exampleManager.loadExamples().then((examples) => {
             this._exmaples = examples;
+            if (!this.hasAnyExamples(this._exmaples)) {
+                // Reset the examples list to get the welcome message (defined in package.json) to appear.
+                this._exmaples = [];
+            }
             this._onDidChangeTreeData.fire(null);
         });
     }
 
+    private hasAnyExamples(nodes?: IExampleNode[]): boolean {
+        return nodes && (nodes.find((node) => node.isLeaf || this.hasAnyExamples(node.children)) !== undefined);
+    }
+
     private createExampleItemList(examples: IExampleNode[]): ExampleItem[] {
         const result = [];
         if (examples && examples.length) {

src/views/app/components/ExampleTreeView.tsx

@@ -7,6 +7,9 @@ import { connect } from "react-redux";
 import * as actions from "../actions";
 import * as API from "../actions/api";
 
+// TODO: I'm pretty sure this entire view is unused and can be removed.
+// See exampleProvider.ts which instead uses the built-in VS Code Tree View API.
+
 interface IExampleViewProps extends React.Props<any> {
     examples: any[];
     loadExamples: () => void;